ESTRO 2024 - Abstract Book

S3650

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

automatically calculated angles and in case a difference of more than 20 degrees was detected, a new treatment plan was optimized using the same optimization objectives to quantify the dose impact of the different beam angle setup. A Wilcoxon signed-rank test was performed to detect if the automated approach delivers equal PTV coverage evaluating near minimum, near maximum and median target dose.

Figure 1: Schematic overview of the tumour grid mapping.

Results:

Beam angle comparison showed that in 65% of the cases the automated beam angles were identical compared to the clinically used beams. In 35% of the cases, a different beam setup was proposed. The clinical as well as the automated approach used mainly full arcs (0° to 360°) or half arcs (0° to 195° or 165° to 360°). The more rare cases (< 100 occurrences, Figure 2) show more spread in start angle and beam range in the clinical plans. Preliminary results (n=15) reveal equal target coverage when comparing near minimum dose (D98%, p>0.05), median dose (D50%, p>0.05) and near maximum dose (D1%, p>0.05). The automated beam setup was able to produce plans with similar target coverage compared to the clinical plans. However, more metrics and more patients need to be included.